Endovascular prostheses are sometimes used to treat aortic aneurysms. Such treatment includes implanting a stent or stent-graft within the diseased vessel to bypass the anomaly. An aneurysm is a sac formed by the dilation of the wall of the artery. Aneurysms may be congenital, but are usually caused by disease or, occasionally, by trauma. Aortic aneurysms, which commonly form between the renal arteries and the iliac arteries, are referred to as abdominal aortic aneurysms (“AAAs”). Other aneurysms occur in the aorta, such as thoracic aortic aneurysms (“TAAs”), which may occur in one or more of the descending aorta, the ascending aorta, and the aortic arch.
Conventional stent-grafts typically include a radially-expandable stent, formed from a plurality of uniform annular stent springs, and a cylindrically-shaped graft material to which the stent springs are coupled. Stent-grafts may be used for reinforcing or holding open the interior wall of lumens, such as blood vessels.
Some commercially-available stent-grafts utilize a set of circumferentially-disposed proximal barbs in order to facilitate long term fixation of the stent-graft at its appropriate landing zone on the wall of a target body lumen in general, and, in particular, a major artery such as the aorta. An additional role of fixation barbs is to facilitate sealing between the distal end of the graft material and the blood vessel neck, so as to prevent endovascular blood leaks around the stent-graft's distal edge, usually referred to as type I endoleaks.